Abstract

Mechanical models of gravity sliding can be used to test the validity of slide-block interpretations. The Coyanosa-Rojo Caballos area of the Delaware Basin, West Texas is a structurally complex subsurface block that is often cited as a gravity slide terrane. Using acceptable block dimensions, our model suggests that low values of the coefficient of friction (≦ 0.23) and elevated pore-fluid pressures must be maintained in the Woodford Shale decollement rocks for sliding of the Coyanosa-Rojo Caballos block to initiate and propagate over regional distances (11 km., 6.8 mi). To date, we have insufficient geologic evidence to support the development of these conditions for the Woodford Shale. Thus, as a result of our preliminary analysis, we conclude that the gravity-slide interpretation of the Coyanosa-Rojo Calallos area is mechanically possible, but questionable on a regional scale.

Although geologically appealing, the slide-block theory requires certain mechanical parameters which we cannot substantiate, with our present data base, on a regional scale. This, however, does not preclude the possibility of gravity sliding on a more local scale.